Fibrous electrical insulation and preparation thereof



iFaienied Apr. 7, i936'y l' f fr FIBROUS'ELECTRICAL INSUL'Il-VIONAND `PREPARA'IION THEREOF f Allert Clifford, ElzabethQN. .'I., assigner 4to?l f l Western Electric Company, Incorporated, NeW York.N.1Y.accrporationdof llewjfcrk'` v Application November 6, 1931, Serial No.j5"7 3,347. j 17 claims. (ci. ,2s-'58) Y This inventionrelates to the preparation'of fl-A g to permitthe flowof a fluid .to and from chambers -brousmaterialsand moreparticularly to amethlIl andlwithout the fluid flowing into chamod of purifying fibrous materials such 'as cotton' kherf. l ,y f

for use as' insulation on electricalk conductors? yYInppractice .thecotton s trandswhichfareto be `l5 Objects of the invention are totremovefsubf` purifiedl are wound or vreeled somewhat-loosely 5 .stantially 'all foreign materials from 1andto purify onporous ilexible hollow cylindrical coreso'rbobffibrous. materialsv such as-'cotton :inl: brous,. bins 29, which are longitudinally compressible. `stranded or textile form by improved methods ,d vA plurality of the packages ofcotton thusformed' that are more convenient, economical and-ef-- are placed on the perferated spindles 27, within f f l cienty than methods heretofore known or use'd.rv Atheves'sel I0,-`as shown at 3l).V Thepackages 30,10

Briefly, Vone embodimentof the invention con-` are placed-One above them other on each spindle, templates enclosing the material in a .pressure until :each pile of packages extends, aboveits chamber and. circulating la bleachingsolution associatedv spindle. A,pressure plate `3 2 which therethrough, lwhereby a verysubstantial;l porcovers the topof tlieupperrnostxpackage, and

l tion of the natural oils and waxes contained in Awhichis provided with a stem 3& whichmay enter 1'5 `thematerial are removed. Thev solution is then n theupper end ofthe .perforatedv tube,k is then rdrained from the chamber, and clear rinse water lplaced 'over each of .theI piles of packages. The may or may not be circulated through the` ma-r cover II is provided on the inside thereof with a terial, as desired; Inorder to effect 'further puriplurality of spring pressedplungers 3 I so spaced cation, a saturated solution :ofcalcinedg'ypsum `vand aligned thatone plunger shall, be d irectlyzll.

is circulated through the material, after'which Vit above each of the 4spindles 2'Iwhen the ,cover III` may again be'rinsed with clear water. Removal is placed in position. As `the cover is loweredr of the material fromthe-pressure "chamber, and` intov position, each of theplun'gers V3I jcompresses thorough drying .completes kthe process; rone of; the pilesy ofpackages of cotton 3 0',l until 251 AOther featuresand advantages of the inventhe tops of the'piles are substantially flush with 25 tion'will-become apparentfrom the following `dethe upper ends ofthe spindles andthe bottoms tailed description of one embodimentthereoby of .the g piles are urgedyagainst the. supporting u means of which the method maybepi'actced, members 34 onthe partitiong I4. The ,plungers reference being had tothe'accompanying drawy are i provided with headfportions 33 which are ing wherein u v Y f urged against the pressure plates. It is thus ap-30 -Fig. lris an elevational vi-eW partly broken away .parent-that the .plungers;` 3l will exert a .pressure of a material treating apparatus, and'- 'l f on plate. 32, which will ybe transmitted to the d l y Fig.'2 is a plan viewrther'eof.- `packages of cotton, and thatsince.`r the ybottom Referring now to`the drawing in which like Lof eachpile is pressed against'thesupporting numerals designatelike parts throughout the sevmember134, and the upper end-of the` pil `e 'is-35,` eral views, the numeral vI 0 Vdesignates a cylindrical covered by the pressure lplatefany fluid that flows vessel having a 'removable coverzII which .may .uplntothe spindles 21 andouvt'through the perbe securely kfastened in .pressure-tight relation rv.foiyations Ato the interior cfl the4 cylindrical aperf to the vessel I0 by means of a plurality of v latches turethrcughthe piles, is prevented from flowing l40. I2. The vessel I0 is provided with abottomIS; outoftheends of the cylindricalv aperture, fandl40 and partitions I4 and I5, which act as false bot- .under Vpressure'it will flow transversely through toms .and divide the yinteriorof the vesselintoa the packages of cotton, and out into the champlurality of chambers` ITI, I'8,and I9. The partiber-ITE 1 l ltion I4' which may or may not be employed ias The bottom I3'of the vessel IIJl has-an'o'pening desiredis provided with a pluralityof openings 33 therein,at which point a'pipe 35 isconnectedi 2| which permit t-heilow of liquid from the chain so as to' 'co nvey fluid to and from the lchamber ber II into the chamber I8, "and the partition` I5 I9. i Thpipes -25 and 35'lead`A froin` the cham' Y is provided witha large central opening`22, which bers ;I8' and I9 respectively, iiithe vessel I0', to leads into a pipe 23, extending throughthe chamyla, reversingwalve 31,l fromV which pipes 38,A and f ber vI9 and through the bottom of thevessel I0 39 lead totheA inlet vand outletpartsrespectively,50 where it connects with-a pipe25. 'I he partition of a centrifugaly pump 4I driven `by an electric yI5 is provided with a plurality-of openings v2li-J8, motor .42. V An` expansiontank is `positioned which are in alignmentwith corresponding openabovefther pump 4I and a; drainpipe 45 `leads ings inthe partition I4 through whichopenings from theJb'ottomy ofy the tank 4Std the pipe 38 hollow perforated 'spindles2'I protrude, sonas `AIso as to dischargev the contents-lof theexpansionq 'Z'ff tank into` the centrifugal pump 4|.` Thefexpan- K 1 'A ,sion tank 43 is also provided with an overflowv pipe 46 leading toa waste discharge systemof ,any-

"suitable type (not shown), to preventthe con# low., hevessel I0 to permit the introduction oi? "steam,into,[the pipes 253 and 35 .,respectively, and Y "tents of theexpansion tank fromoverfiowing.

team inlet pipes 48 and 49 rare provided be# thevesselvv I D 'is provided with pressure *'augs ascertained, rand a valve 56 i`s` providedto' reg latefthe ow of iluid throughvv thepipe` 53 when A fdesired.. VA drain valve 51 is pro'videdfdjacent Vtoand in the same line with the revers"in gfvvalvey `31,;to drain'y the uidirom thesysteminto a waste discharge *pipe 59 which: leads to', a*W:aste?`dis'- chargesysteminot sh'cirrriic` yAnfauXiliary{drain pipe 60 leads `fromy the pipe 25 througha valve-1M v "'tofthe' Wastedischarge pipe 59.* y A` `wate1f 'supply 'plp'e '634 is "connected lfrom a sourcey offwa [(notf shown) i through a vallvfe'lto the"expansien'A tank v f"f Q A flg'; Whenfaouantity of cotton-has' beenfmadelup jintd packages 30 ,y 1and the cotton isto be p'uriiied ,f the packages are disposed on theisp'indle' 2 1? until they. are iilled, 4fas^previously"jdescribedgw- The.

` cover! `l I; is" then ioweredinto prece, and! is se- 1' r Whilethe kabove described apparatuawhichfis @commonly known *as a" IFranklintdyeinir maf' `chlnelfisrwellsuited forperiormingr @i155 ltration :of impurities is,kept,low. w

Achresvsttnj; This 'willi permit, a. subset;itgiaiiy,.` equalriquantity `oi'ffresh purifyingk fluid to` riterf` ,f- `thesapparatus,from the`eirparlsiori*tan*43.l By @meaxofzy this ,arrnsementpurifyingj fluid that' 91s,. contaminated Iwith .impurities is@ 4oritipnuvallyv escaping@ from` thewapparatus; .and h `vviiinv winfrfiiekreinartente .described in detail, L

, arose-,25e y other forms of' apparatus,` such for example as the ffhiesldyeing machine and the Obermaier dyeing machine, which operate on asimilar principle, may be satisfactorily employed. Also, 7 slncetheabovedescribed apparatus may be employed in numerous ways in preparing'and treatingy tibi-fous materials, in `order that the invention which maybe included the natural oils and waxes, and the;V ionizableorI electrolytic impurities, which *consist principally finorganic compounds, such ascompounds vcontaining the alkali metals. The j rionionizable impurities maynot, under certain cirtnimstances,4 have `adeleterious effect upon the [main-in the cotton;` ,i l y .c ;The removalgof the 'ionizable' impurities is very important when cotton "is to.` be 'used for v'insulat- {ing .purposes-These impurities, iffpermittedeto Temri the Cotton, may,y under f the 'influence e ,ofgr moisture becomevgrather'fhighly Sconductiv'e, 2 thus greatly'reducing ,the` insulationlresistance.of the;cotton,therebypartiallyjdestroying its value as a,1if1.eetr-crmftterial'.,y Le y Y 4, vThe f removal oiy vbothfxtypes of l impurities; may be, actoraplished'finy lthexabove .described appara# tus,withoutgdisturbingno1-removing the. contentsy ioffthemae'chine duringithe process.; `It has been :found preferable `-to* perform; the operation' of removing fr, non-ionizable :,1 irnpuritiesl before' removpackagesare placedwony the spindles'in the con- -.,tainerl-9, als'oinythe znannerfalsol hereinbefore described, .andihefccvecl bis secured-11n p1ace..-. a y. e f .frneimum ,.tiwttj-timsiy been around.; pmicumriy` .-suited'torenioveithe natural voils andwaxes from i l the.' cottonis a water'solut'ion of *sodiumA hydroxide, e *having` la] '|510''ncentratioifrfoffA approximately one pound o the"` hydroxide jperfone hundred gallons I f Insteadgf sodium,nydroxidepother agents be employed, su'chffor e exy lutionL may@eA rlepared, `in any; convenient coria'iner, [and then"` introduced Tinto the expansion jta'nk, orgit prepared inthe expansion tank, by adinitutinf:`vvat`e1j froml the source voi?I supply, .faddinathe sodiumhydroxide, and kstirring to efffectcomplete, ,solution4 of the-base. The system is ''.thenfready `for ,circulation of the solution, which .rr'utygbey accomplishinggby,adjusting thegi'eyersing valve-ltogpermit the solution toenterthe chamber In, afterzgwhich ther pumpiis started. It; has y*been 191mg', `prefexfable' Wto: circu1ai.e` the solution from andy ether hyd'rOXideSr The l ftank, and may becirculated for av fewniinutes in inside to outside initially', a path that has been previously described.- However, it is not'jessential that the solution be circulated inthis'path, and satisfactory results rnayv be' obtained by" initially circulating'thersolution from'v outside tolinsidc.'

temperatures higher than the above. Also, it has been foundthat .the best results are obtained by maintaining the: temperature; aboutH 90, Fahrenheit.

After'the solution "has been circulated a p r'e determined length of time, the` pump-may be stopped, and the solution, containing` theo'ils "and waxes yhave been removed, Imay. be ydrawnioff through the outletand permitted to escape to the drain.` `.The circulation of the sodium hydroxide may have,V leftrk in the cottonoflbres 1"small,.quantities Of-Water soluble impurities, such asthe base itself or compounds derived'therefrom;l Portions ofl these impurities may convenientlyobe removed, before the further purification of .the cotton with reagents, by circulating clear water, through the cotton,` and the amount of impurities tobe subsequently removed will thereby be reduced. The

washing maybe done rby introducing clear water into the expansion tank, starting the pump and circulating the water for a short period of time,

after which it kisl permitted to escape through the drain. It should be understood. that therinsing with clear water is not arequired operation, and .that-itmay be performed or not, asfdesired. Y y

The purifying liquid that is employed to remove rthe ionizable impurities consists yof, ra saturated solution of best grade calcined gypsum in water. One form of calc ined gypsum, which is also known as plaster of Paris, isobtaina'ble commerciallyy as No. 1 moulding plaster. r.Thelsoperations of `dis- .solving;the calcined gypsum and of circulating the solutionmay be performedin -a manner similar to thoseemployeld in preparing and circulating the sodium hydroxide,solution'.`r In icon-A nection with the circulation of lthis purifying solution it has been found preferable to circulate initially from insidev to outside of the packages of cotton, but the initial circulation'may be in the opposite direction, and the direction of vcirculation may be changed as many times as desired during the process.

" It has been found that thepurification maybe satisfactorilyweonducted at temperatures ranging from 90 to 100 Fahrenheit. Between these ternperature limits gypsum exhibits substantially maximum solubility. While particularly satisfactory purification of cotton may be accomplished between these temperature limits, it is to be understood that the process may satisfactorily be conn ducted at lower or higher temperatures, if suc variation is found to be desirable. Y

`After the process has been conducted a predetermned length of time, the pump may be stopped, and the contaminated solution may be' permitted to escape from the apparatus to the waste discharge system. The packages of cotton may then be removed from the vessel I0, or if it may appear desirable to give the cotton a rinse, clear water may be introduced into the expansion the same manner in whichthe purifying -solution was circulated. "The cotton mayrthen be removedA from the apparatus an'dthoroughly dried inany convenient manner.

The use of calcined gypsum affords numerous advantages which' make the process ofy purifying cotton described: herein particularly desirable. I'hemgypsumr is carried into thebres of theV cot ton lto 'a'y large extent andv vin *a :very/'satisfactory 'expensive material,y and the 'cost'of preparing vthe rcotton for use -as insulation is 'quite low'. s 's ,'While the exactlfunction, performed by the" calcin'cdgypsur' in the abovedscribed methqdm treating cotton is notclearly understood, it-is believed'thatentire molecules or parts'o'f moleculesv of jthereadily soluble and'ionizableinorganic'impurities' found in' orv onfv the fibres of cotton/are replaced i")y'moleculesor parts o f molecules of the relatively insoluble and noijr-ioniaable calcium sul'- phate inA 'the solution u ofv5 calcinedj-gypsum "employed in treatingfthecotton.y `Experinients seem 1 to'indicatethat the cottonV bres'havean afnitv for thev calcium cations present in the'solutionof calcined gypsumk and that the'cfa'lcium'cations are substantially ,irreversiblyjy adsorbed bythe cotton mannerfFurtherrnore, calcined gypsum is an in'- l 'fibres in preference tothe more readily r`ioxfiiznable cations present in thecotton, suchffor example,

.as those/ofthe alkali metalsgmWhat'ever the true 'function of the solution offcalcined gypsum may be, theuse of kvsuch asolution forv treating cotton in accordance with the method hereinbefore'def scribedresults in suchamarked improvement in f the electrical insulating properties'of the cotton that it maybe satisfactorily substituted for .the

usual insulating silk inimanycases,particularlyy for useuncler conditions offhigh humidity where the presence ofY ionizable impurities is' deleterious.

`Although the preferred pathof circulation has beenfound to be from inside to" outside of the packages of cotton, the invention isf not limited to that method'of'opera'tiom assatisfactory results can be obtained by `circulating 'the solution'from outsidel to 'infside'gof the packages. e Similarly,

bothmethods maybe used'alternatly during' vthe process of purifying thefcotton, and there may be aS'fma'ny reversalsof the'direction'offlow as may seem desirable.- f

While the-method ofjtreating cotton hasbeen described herein as a singley process, consisting ,of steps whereinV twonvidely different vtypes [of impurities may be removed from cotton, it is'not intended that the process shall be limited to'these steps. cotton may be applied, it is intended to be within the scope `of this invention, that the purification of cotton may be confined exclusively to the process for removing natural oils and waxes, or f that it may be confined to the removal of ionizable impurities. e.

It should be understood that while the process of purifying cotton herein described is well adapty edfor the puriilcation of cotton in the form of strands wound into packages, it is not confined to this arrangement alone, as the processv is well suited to the purii'lcation'of cotton in all forms such, for example, as unspun raw cotton fibre or' woven cotton fabrico Y Although the description of the invention has included but a single method whereby it may be practiced, theinvention is not to be construedas limited to that method, as many modifications in the method and apparatus may be made, within the scope of the appended claims.

Depending upon the uses to which the 

